a term applied to various kinds of involuntary, rapid, nonrhythmic contractions of individual muscle groups and muscle fibers. Myoclonia is considered a form of hyperkinesia.

There are three types of myoclonia: true myoclonia, which is characterized by jerky movements of the extremities due to the contraction of large groups of muscles; paramyoclonus, which is characterized by the contraction of individual muscle fibers; and myorhythmia, which is characterized by the constant, rhythmic twitching of an individual muscle. Myoclonia is caused by inflammatory, degenerative, and toxicoallergic processes in the extrapyramidal system. It is one of the principal symptoms of myoclonus epilepsy. Myoclonia may also accompany tick-borne and epidemic encephalitides and other diseases.

Treatment involves elimination of the underlying disease and prescription of antispasmodics. Early diagnosis and treatment of encephalitis are important in preventing myoclonia.